Telephony and telegraphy.



S. G. BROWN.

TELEPHONY AND TELEGRAPHY.

APPLICATION FILED DEO.12,1910.

Patentbd Mar. 11, 1913.

UNITED STATES PATENT OFFICE.

, SIDNEY GEo'EoE BROWN, 0E LONDON, ENGLAND.

TELE HONY AND TELEGRAPHY.

Specification of Letters Iatent.

Patented Mar. 11, 1913.

Application filed December 12, 1910. Serial No. 596,904.

- contacts or electrodes of which the resistance between them iscontrolled by local means; the object being to render the soundcharacter and to render possible of employment minute or imperfectsounds or signals so that the same may be magnified, transmitted andreceived or recorded with more expedition accuracy and clearness than bythe methods ordinarily employed.

According to this invention the resistance included at the point ofcontact of the electrodes is regulated by a local electromagnet the coreof which is provided with a sheathing of copper or other metal, saidsheath ing serving, by reason of the eddy currents set up therein,to'maintain the action of the electromagnet constant by excluding fromthe winding thereof the ill effects of the rapidly varying currentswhich traverse the contacts. The same effect may also be obtained byshunting the electromagnet with a suitable resistance or capacity.

The variable resistance contact device may comprise contacts orelectrodes composed of carbon, metal or of carbon alone or ofosmium-iridium and mounted in adjustable relation to each other. To thisend they are respectively mounted on an adjustable arm, and a reed,tongue or strip which may be formed of hardened tempered steel;

the latter being influenced by the line and by the aforesaid localelectromagnet. By utilizing a reed, tongue or strip for carrying thecontact or conductor, outside disturbance may be avoided. The vibratingmember is adapted for adjustment by means of a curved or knife edgebearing.

.In order that the said invention may be clearly understood and readilycarried into effect I will proceed to describe the same 'with referenceto the accompanying draw ing, in which Figure 1 is a side view ofaninstrument embodying the present invention showing the casing insection and the cover in the open position. Figs. 2 to 4 arediagrammatic views of the electrical connections for the saidinstrument.

The aforesaid contacts or electrodes which may be pointed as regards theone and flat as regards the other, or be composed of powdered or'finelygranulated material,

such as carbon, metal, or osmium-iridium,

are indicated at a a, the former of which is carried by a hinged orpivoted arm a and the latter a by a reed, tongue or strip 0, of hardenedtempered steel or other suitable material capable of being vibratedunder the influence of an electromagnet 1) arranged in the line and of alocal electromagnet 1) arranged in the circuit of the local battery orsource of current 0'; these electromagnets being shown as superimposed.The arm a which carries the contact a is hinged or pivoted at a to theframing a of the instrument in such a manner as to permit of the armbeing turned into the position shown in broken lines when required toadmit of cleaning or otherwise operatin upon or inspecting the contactsa a. he arm a is arranged so that its free end a rests upon or against ascrewed stud or similar devices b whereby the position of the contact athereon may be adjusted relatively to the contactva" carried by the reedor strip a. This latter may be secured to the framework a of the devicealso with a capability of adjustment and with this object in view theextremity (1 thereof remote from the contact-o is attached to theaforesaid framing by means of suitable studs, screws or the like b, bthe necessary adjustment of the reed a may be readily effected bymounting the same upon a bearing surface 1) b ef curved or knife form sothat a tilt may be given to the reed in the one or the other direction.By thus mounting the vibrating contact a on a reed tongue or strip asuch as herein referred to the harmful effects due to outsidedisturbances experienced when the contact is mounted on a diaphragm ordisk are avoided and improved working is obtained.

The windings 'c c of the electro-magnets b b -are mounted upon a core 0'and the winding 0' of the e'lectro-magnet b which carries the linecurrents to be magnified and the winding 0 of the local elect-ro-magnetboth act upon the reed, tongue or strip a pertaining to the contact orelectrode (1' when the arrangement is in operation. The core 0 of thelocal electro-magnet is provided with a sheathing or lagging 0 of copperor other metal, in the form of a tube or a winding which serves tomaintain the action of said electromagnet constant ,If

a winding f (Fig. 4) be used the ends maybe brought out to terminals f fand the circuit completed by. placing a resistance ff an inductance f ora capacity f across the same. The instrument is arranged within a casinge which is provided with a hinged cover 6' so as topermit of the arm abeing turned out of the Way to allow the contacts a a to be inspected orcleaned.

The local or magnifying circuit contains a battery or other source ofcurrent 0 the cont-acts a a, the windings c of the local electroniagnetb the primary 0 of a transformer a pertaining to the receiver ortransmitter and theusual galvanometer or other instrument 0 whereby therequired indication may be obtained such as that of the current thatflows through the contacts, thereby indicating the resistance betweenthe same. Owing to the increased resist ance ottered by carbon, itisnecessary, tosuccessful working to increase the resistance of the. localcircuit over that which would be necessary if metal contacts were used;the latter as is well known being of higher electrical conductivity. Thewinding .0 of'the localeleetromagnet b may be-shunted by a re-' sistanced or by a suitable capacity Fig. 4; the bulk of the local currenthowever passes through the winding of the magnet. \Vhen the core 0 ofthe local electromagnet is lagged or covered with a copper sheathing 0(Figs. 1 and 2); the shunt resistance 1] or capacity may be dispensedwith. The

improved arrangements permit of stronger currents being employed in thelocal circuit and the magnification of the signals, or sound waves willbe increased owing th the greater energy available in this circuit.

'hat I claim and desire to secure by Let-- ters latent of the UnitedStates is:

I. In an apparatus for the electrical transmission and reception ofsignals, the combination in a, microphonic resistance varying device, ofa hinged member, an electrode mounted on said member, a vibratorymember, a knife bearing forsaid vibratory member, means for adjusting.said member on the knife bearing, an electrode on said vibratory memberacting in. conjunction with the previously mentioned electrode, anelectro-magnet for controllingthe resistance be tween the coactingelectrodes, and means for preventing the ill effects of the "aryingcurrents which traverse the electrodes from entering the winding of thesaid electromagnet. I

2. In apparatus for. the electrical trans mission and reception ofsignals, the combi nation in a microphonic resistance'varying device, ofa hinged member-, a'carbon electrode mounted on said 'member a vibratorymember, a carbon electrode thereon acting in conjunction with thepreviously mentioned electrode, a knife bearin for said vibratorymember, screws for adjusting the vibratory member onthe knifebearing, anelectro-magnet for controlling the resistance between the coactingelectrodes, and a copper lagging on the. core of said electromagnet forpreventingt-he ill effects of the varying currents which traverse theelectrodes from entering the winding of said magnet. I

In testimony whereof I attix my signature in presence of two witnesses.

SIDNEY GEORGE BROIVN. \Vitnesses B. Smwure Sntirn, G. ll. \VARREN.

